Yep i agree with Paul,, dont see the problem in using the earth supplied from the supply company.
An electrician i know wires camp sites.. the electric hook ups.. he installs the cable to the posts as a PME supply, then disconnects the earth from the socket, but connects it to an earth stake, making it a TT connection..
WHY>> i just dont see the point as long as you have you disconnection times etc..
